So carry on for the best Explanation on Xref's.
An external reference is a pointer that resides in a drawing . The pointer
references another drawing that is external to the parent drawing. A referenced drawing is
visible within the parent drawing.
• External references (XREFs) are useful in an environment where a team of drafters is working on a project, with each person constructing individual components of the
project. Each team member can view drawings belonging to others, so that changes
are handled and drawings stay synchronized.
• To create an XREF, you attach a referenced drawing to a parent drawing. An attached
XREF appears as a single entity on the current layer in the parent drawing, similar to
an inserted block.
• Referencing a drawing is different from inserting a drawing. Inserting a drawing takes
a snapshot of a drawing in its current state. The snapshot is not updated if the inserted
• On the other hand, when you open a drawing that contains an XREF, you see the
most recently saved version of the referenced drawing.
• A drawing can contain multiple XREFs.
• A drawing can reference another drawing, which may reference yet other drawings,
which may result in nested XREFs. A nested XREF is one that is attached to a parent
drawing through another drawing.
• A drawing can be both a parent and an XREF.
• Two drawings can reference each other, resulting in a circular reference.
There is a set of operations you can perform on an XREF:
• You can open an XREF drawing to edit it from within the parent drawing.
• You can unload an XREF to remove it from your display.
• You can reload an XREF to force AutoCAD to re-read the XREF drawing file.
• You can detach an XREF drawing from the parent.
• You can bind certain objects or an entire XREF drawing into a parent.
• Objects you can bind are called named dependent objects.
• You can change settings of referenced layers from within the parent drawing. Layer
settings affect only the parent drawing and do not affect layer settings in the
• You can clip unneeded portions of XREF drawings, saving system resources, thus
Inserting an XREF
The XATTACH command provides one way to specify a drawing file to be referenced
into the current drawing as an XREF.
Command line: XATTACH
Pulldown: Insert DWG Reference…
When you invoke XATTACH, the Select Reference File dialog box appears, where you can navigate to and select the drawing you want to reference.
When you have selected a file, the
External Reference dialog box
appears, where you
can specify the reference type,
insertion point, scale factors, and
rotation angle. Check the
appropriate boxes if you wish to
specify any of these items on
screen instead of here in the
The Squares drawing appears in the Circles drawing
• The reference type determines whether XREFs are nested.
• The reference type can be attachment or overlay.
• A referenced drawing that is an attachment is visible in the parent of its parent drawing. It is called a nested XREF.
• A referenced drawing that is an overlay is not visible in the parent of its parent drawing .
• The default reference type is Attachment.
• Overlays are recommended to prevent unduly complicated XREF configurations.
• If all Reference types are Attachments, then all XREF drawings are visible in all drawings all the way up the chain.
• Drafters further up the chain may be unnecessarily loading and viewing XREFs that
they don’t need.
• Using Overlays breaks the chaining created by attachment XREFs.
• Using overlays means all drafters must choose which drawings to XREF into their drawing.